Science Does Not Support the 'Rule of Seven' for Relationships

Chris Martin and Jennifer Lawrence are fine

September 1, 2014

Bloggers and busybodies are divided over whether or not the age difference between actress Jennifer Lawrence, 24, and musician Chris Martin, 37, automatically renders their relationship inappropriate. Daily Mail “relationship expert” Tracey Cox condones it, saying their common ground should count for more than their 13-year age gap; other commenters, meanwhile, condemn Martin as “creepy” and Lawrence as “lame.”

If you subscribe to the “rule of seven,” the question of where the boundaries of a socially acceptable relationship lie aren’t a matter of opinion—they’re clearly defined. According to the rule, the age of the younger partner (regardless of gender) should be no less than seven more than half the older partner’s age. Martin, then, shouldn’t date anyone younger than 26 and a half; Lawrence shouldn’t go above 34.

The rule is widely cited, but its origins are hard to pin down. In its earlier incarnations, it seemed to be a prescription for an ideal age difference rather than the limit of what’s okay. In The Moon Is Blue, a 1953 film adaptation of the 1951 play by Frederick Hugh Herbert, Maggie McNamara—playing 22-year-old Patty O’Neill—asks her 30-year-old suitor, “Haven’t you ever heard that the girls is supposed to be half the man’s age, plus seven?”

The rule also appears in The Autobiography of Malcolm X. In the 1950s, Nation of Islam leader Elijah Muhammad “taught that a wife’s ideal age was half the man’s age plus seven”; this age gap should make up for women’s maturing more quickly than men, as well as ensure that the husband was sufficiently authoritative over his wife. When Malcolm X met his future wife Betty Sanders, he interpreted the fact that their ages fit the rule of seven as a sign that they were destined for each other. Muhammad might not have been the most reliable relationship counselor, though; he was also concerned about height disparity: “a tall man married to a too short woman, or vice versa … looked odd, not matched,” he preached.

But the rule of seven may not actually describe what people consider acceptable. In 2001, a team of Dutch social psychologists, led by Bram P. Buunk of the University of Groningen, examined desired minimum and maximum ranges across different ages by approaching people in public spaces—railway stations, libraries, malls—and asking them (anonymously) what ages they would consider appropriate for five different levels of relationship: marriage, serious relationship, falling in love, casual sex, and sexual fantasies. They restricted their survey to people who fell within a year of five age groups: 20, 30, 40, 50, and 60, and asked a similar number of men (70) and women (67). They found that women’s preferences were fairly consistent over time: Throughout their lives, women tended to prefer men who were around their own age, with a range from a few years younger to a few years older—even in fantasy-land. For men, though, the difference between their own age and what they considered an acceptable minimum increased as they got older, with the most dramatic drop around age 40: “Men of 40, 50, 60 all seemed to show an interest in partners for sexual fantasies and casual affairs that extended down into the mid to late 20s.” The lower the level of involvement, the lower the minimum age.